tmp

Author: hmarui66

src/main/kotlin/simpledb/index/btree2/BTree.kt

@@ -3,12 +3,65 @@ package simpledb.index.btree2
 import simpledb.query.Constant
 
 class BTree {
-    fun search(key: Constant): BottomInternalNode {
+
+    // 検索してリーフの一つ上の中間ノードを返す
+    // 返されるノードの共有 latch はかけられたままとなる
+    fun search(key: Constant): BottomInternalNode? {
+        // ルートを取得
+        val root = getRoot() ?: return null
+
+        var success = false
+        var index: Int
+        var parent = root
+        var child: InternalNode? = null
+
+        try {
+            do {
+                check(parent.getEntrySize() != 0) {
+                    "parent with 0 child"
+                }
+
+                index = parent.findEntry(key)
+
+                child = parent.fetchWithoutLatch(index, key)
+
+                // 無限ループにならないか？
+                if (child == null) {
+                    parent = getRoot() ?: return null
+
+                    continue
+                }
+
+                // child を latch
+                // BottomInternalNode は常に排他 latch がされている前提
+                child.latchShared()
+
+                parent.releaseLatch()
+                parent = child
+
+                child = null
+            } while (!parent.isBottom())
+
+            success = true
+            return parent as BottomInternalNode
+        } finally {
+            if (!success) {
+                if (child != null && child.isLatchOwner()) {
+                    child.releaseLatch()
+                }
+
+                if (parent != child && parent.isLatchOwner()) {
+                    parent.releaseLatch()
+                }
+            }
+        }
+    }
+
+    private fun getRoot(): InternalNode? {
         TODO()
     }
 
     fun insert(leaf: Leaf) {
         TODO()
     }
-
 }

src/main/kotlin/simpledb/index/btree2/BottomInternalNode.kt

@@ -1,7 +1,21 @@
 package simpledb.index.btree2
 
+import simpledb.query.Constant
+
 class BottomInternalNode {
     fun delete(idx: Int) {
         TODO()
     }
+
+    fun findEntry(key: Constant): Int {
+        TODO("Not yet implemented")
+    }
+
+    fun getTarget(index: Int): Leaf {
+        TODO()
+    }
+
+    fun releaseLatch() {
+        TODO("Not yet implemented")
+    }
 }

src/main/kotlin/simpledb/index/btree2/InternalNode.kt

@@ -0,0 +1,33 @@
+package simpledb.index.btree2
+
+import simpledb.query.Constant
+
+class InternalNode {
+    fun isBottom(): Boolean {
+        TODO()
+    }
+
+    fun getEntrySize(): Int {
+        TODO()
+    }
+
+    fun findEntry(key: Constant): Int {
+        TODO()
+    }
+
+    fun fetchWithoutLatch(index: Int, key: Constant): InternalNode? {
+        TODO()
+    }
+
+    fun latchShared() {
+        TODO("Not yet implemented")
+    }
+
+    fun releaseLatch() {
+        TODO("Not yet implemented")
+    }
+
+    fun isLatchOwner(): Boolean {
+        TODO()
+    }
+}

src/main/kotlin/simpledb/index/btree2/Leaf.kt

@@ -1,4 +1,3 @@
 package simpledb.index.btree2
 
-class Leaf {
-}
+class Leaf

src/test/kotlin/simpledb/index/btree2/BTreeTest.kt

@@ -0,0 +1,24 @@
+package simpledb.index.btree2
+
+import org.junit.jupiter.api.Assertions.*
+import org.junit.jupiter.api.Test
+import simpledb.query.Constant
+
+class BTreeTest {
+    @Test
+    fun retrieveLeaf() {
+        val key = Constant(1)
+        val tree = BTree()
+
+        val bin = tree.search(key)
+        checkNotNull(bin)
+        try {
+            val index = bin.findEntry(key)
+            assertNotEquals(index, -1)
+            val leaf = bin.getTarget(index)
+            assertNotNull(leaf)
+        } finally {
+            bin.releaseLatch()
+        }
+    }
+}